The present invention relates to a stretcher such as a wheeled stretcher for use in a hospital, and particularly to a wheeled stretcher having a wheel that can be deployed to contact a floor along which the stretcher is being pushed. More particularly, the present invention relates to a wheeled stretcher having a motorized wheel.
It is known to provide hospital stretchers with four casters, one at each corner, that rotate and swivel, as well as a center wheel that can be lowered to engage the floor. See, for example, U.S. patent application Ser. No. 09/150,890, filed on Sep. 10, 1998, entitled "STRETCHER CENTER WHEEL MECHANISM", for Heimbrock et al., now U.S. Pat. No. 5,987,671, which patent application is assigned to the assignee of the present invention and incorporated herein by reference. Other examples of wheeled stretchers are shown in U.S. Pat. No. 5,806,111 to Heimbrock et al. and U.S. Pat. No. 5,348,326 to Fullenkamp et al., both of which are assigned to the assignee of the present invention, and U.S. Pat. No. 5,083,625 to Bleicher; U.S. Pat. No. 4,164,355 to Eaton et al.; U.S. Pat. No. 3,304,116 to Stryker; and U.S. Pat. No. 2,599,717 to Menzies. The center wheel is typically free to rotate but is constrained from swiveling in order to facilitate turning the stretcher around comers. The center wheel may be yieldably biased downwardly against the floor to permit the center wheel to track differences in the elevation of the floor. The present invention comprises improvements to such wheeled stretchers.
According to the present invention, a stretcher for transporting a patient along a floor includes a frame, a plurality of casters coupled to the frame, a wheel supported relative to the frame and engaging the floor, and a drive assembly drivingly couplable to the wheel. The drive assembly has a first mode of operation decoupled from the wheel so that the wheel is free to rotate when the stretcher is manually pushed along the floor without hindrance from the drive assembly. The drive assembly has a second mode of operation coupled to the wheel to drive the wheel and propel the stretcher along the floor.
According to still another aspect of the present invention, a stretcher for transporting a patient along the floor includes a frame, a plurality of casters coupled to the frame, a wheel coupled to the frame and engaging the floor, a push handle coupled to the frame to maneuver the stretcher along the floor, a drive assembly selectively couplable to the wheel and being operable to drive the wheel and propel the stretcher along the floor, and a hand control coupled to a distal end of the push handle to operate the drive assembly.
In accordance with a further aspect, the drive assembly includes a motor having a rotatable output shaft, a belt coupled to the output shaft and the wheel, and a belt tensioner movable to tension the belt so that the belt transfers rotation from the output shaft to the wheel.
According to a still further aspect, the belt tensioner includes a bracket, an idler coupled to the bracket, and an actuator coupled to the idler bracket. Illustratively, the actuator has a first orientation in which the idler is spaced apart from or lightly contacting the belt, and a second orientation in which the idler engages the belt to tension the belt to transfer rotation from the drive motor to the wheel.
In accordance with another embodiment of the drive assembly, the wheel is mounted directly on an output shaft of a drive motor. In accordance with still another embodiment of the drive assembly, the wheel is mounted directly on a rim portion of a rotor of a drive motor.
In accordance with another aspect, the stretcher further includes a battery supported on the frame and an on/off switch coupled to the drive motor and the actuator. The on/off switch has an "on" position in which the drive motor and the actuator are supplied with electrical power, and an "off" position in which the drive motor and the idler bracket actuator are prevented from receiving electrical power.
In accordance with still another aspect, the second mode of operation of the drive assembly includes a forward mode in which the drive assembly is configured so that the wheel is driven in a forward direction, and a reverse mode in which the drive assembly is configured so that the wheel is driven in a reverse direction. Illustratively, movement of a control to a forward position configures the drive assembly in the forward mode, and to a reverse position configures the drive assembly in the reverse mode. In one embodiment, the control includes a rotatable switch coupled to a distal end of a push handle, and which is biased to a neutral position between the forward position and the reverse position. In another embodiment, the control includes a push-type switch coupled to a distal end of a push handle to control the speed of the drive motor, and a forward/reverse switch located on the stretcher to control the direction of rotation of the drive motor.
According to another aspect of the invention, a stretcher for transporting a patient along a floor includes a frame, a plurality of casters coupled to the frame, a first assembly coupled to the frame for rotatably supporting a wheel between a first position spaced apart from the floor and a second position engaging the floor, a selectively engagable clutch configured to selectively couple a drive motor to the wheel when the clutch is engaged. Illustratively, the clutch allows the wheel to rotate freely when the stretcher is manually pushed along the floor without hindrance from the drive motor when the wheel is engaging the floor and the clutch is disengaged. On the other hand, the drive motor drives the wheel to propel the stretcher along the floor when the wheel is engaging the floor and the clutch is engaged.
Additional features of the present invention will become apparent to those skilled in the art upon a consideration of the following detailed description of the preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.